Notes on Heat and temperature | Grade 8 > Science > Heat | KULLABS.COM

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#### Heat

Heat is the sum of kinetic energy of all molecules of a substance. We use the expressions of hot and cold in our daily life on a number of occasions. We use heat for cooking food and keeping our body warm. We can get heat from coal, gas or electricity and sun. The degree of hotness and coldness of an object is called its temperature. Temperature is usually measured in the Celsius scale or Fahrenheit. The normal human body temperature is 98.40 Fahrenheit or 36.90 Celsius.

#### Temperature

Temperature is a measure of how hot or cold a body is. Temperature is usually measured in the Celsius scale or Fahrenheit scale. Temperature of the system can be defined as the property that determines whether or not the body is in thermal equilibrium with the neighbouring system. If the number of systems is in thermal equilibrium, this common property of the system can be represented by the simple numeric value called temperature.

Differences between Heat and Temperature

The differences between heat and temperature can be summarised in points as follows:

 S.N Heat S.N Temperature 1. Heat is the form of energy that flows from the system to its surroundings. 1. Temperature is the result of heat. 2. Mass of the body affects the total heat. 2. Mass of body does not effect on temperature but depends on the molecular vibration of the body. 3. Heat is measured in joules or calories. 4.2 Joules = 1 calorie 3. Temperature is measured in degree Celsius or degree Fahrenheit or Kelvin Scale. 4. Heat is measured by using a Calorimeter. 4. Temperature is measured using the thermometer.

• Heat is the sum of kinetic energy of all molecules of a substance.
• We use heat for cooking food and keeping our body warm.
• We can get heat from coal, gas or electricity and sun.
• The degree of hotness and coldness of an object is called its temperature.
.

### Very Short Questions

 S.No. Heat Temperature 1 Heat is a kinetic energy of all molecules of a substance. Temperature is the degree of hotness and coldness of a body. 2 Its SI unit is joule. Its SI unit is Kelvin.

The two common scales of the temperature are the Celsius scale and the Fahrenheit scale.

The temperature of pure melting ice and that of steam on the Celsius scale is 0 degree centigrade to 100 degree centigrade.

\begin{align*}\frac {(K-273)}{100}= \frac {(C-0)}{100} \\ \text {or,}\: (100 – 273) &= C \\ \text {or,}\: C &= -273 + 100 \\ \text {or,}\: C &= -173 \\ \text {Thus,}\: 100\:K &= -173^o\:C. \\ \end{align*}

\begin{align*} \frac {(C – 0)}{ 100} &= \frac {(K- 273)}{100} \\ \text {or,}\: 220 &= K-273 \\\text {or,}\: K &= 273 + 220 \\ K &= 493 \\ \text {Thus} \: 220^o\:C &= 493\: K \\ \end{align*}

\begin{align*}\frac {(C-0)}{100} &= \frac {(F-32)}{ 180} \\\text {or,}\: \frac {30}{10} &= \frac {(F-32)}{18} \\\text {or,}\: 30 \times 18 &= (F – 32) \times 10 \\ \text {or,}\: 540 &= 10F – 320 \\ \text {or,}\: 540 + 320 &= 10F \\ \text {or,} F = \frac {860}{10} \\ \text {Thus}\: 30^o\:C &= 86^o\:F \\ \end{align*}

One calorie is the amount of the heat required to raise the temperature of one gram of water by 1°C.

$$\frac {(C – 0)}{100} = \frac {(F – 32)} {180} = \frac {(K – 273)} {100}$$

0%

degree

Joule

kilogram

meter

Speedometer

Barometer

Thermometer

Odometer

• ### The hotness on an object is determined by its ______.

pressure

none of these

heat

temperature

• ### The temperature of boiling water cannot be measured by ______.

laboratory thermometer

clinical thermometer

both clinical and laboratory thermometer

• ### A wooden spoon is dipped in a cup of ice cream , its other end ______.

becomes cold

becomes hot

becomes cold by the process of radiation

does not become cold

0°C

100°C

357°C

39 °C

• ### Higher the temperature of the body ______ the kinetic energy of the molecules of that body.

Same

Higher

none of these

Lower

• ### What happens to the object when heat energy is supplied to it?

the object gets hot
the molecules of the object moves faster
the molecules gets far apart from each other
• ### The device that measures the degree of hotness and coldness of a body is called ______.

temperaturemeter

lactometer

thermometer

calorimeter

ethanol

mercury

water

alcohol

• ### Process of division of temperature scale in thermometer is called ______.

division of thermometer

separation of scale in thermometer

marking of thermometer

calibration of thermometer

• ### The advantages of using mercury in a thermometer is ______.

it can be used to measure wide range of temperature

the calibration of mercury is easier as it expands uniformly at ordinary temperature

all of the answers are right

it does not stick in the glass

• ### Clinical thermometer was invented by ______.

Sir Arthur King

Sir Clifford Allbutt

Sir Isaac Newton

Graham Bell

1850 A.D.

1860 A.D.

1890 A.D.

1870 A.D.

• ### The thermometer used to measure the maximum and minimum temperature of a day is called ______.

day and night thermometer

clinical thermometer

maximum and minimum thermometer

horse shoe thermometer

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